已知sin(3π+a)=2cos(a-4π),求(5sin(π/2-a)+cos(π/2)-a))/(2cos(π+a)-sin(-a))的值
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![已知sin(3π+a)=2cos(a-4π),求(5sin(π/2-a)+cos(π/2)-a))/(2cos(π+a)-sin(-a))的值](/uploads/image/z/3912493-13-3.jpg?t=%E5%B7%B2%E7%9F%A5sin%283%CF%80%2Ba%29%3D2cos%28a-4%CF%80%29%2C%E6%B1%82%285sin%28%CF%80%2F2-a%29%2Bcos%28%CF%80%2F2%29-a%29%29%2F%282cos%28%CF%80%2Ba%29-sin%28-a%29%29%E7%9A%84%E5%80%BC)
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已知sin(3π+a)=2cos(a-4π),求(5sin(π/2-a)+cos(π/2)-a))/(2cos(π+a)-sin(-a))的值
已知sin(3π+a)=2cos(a-4π),求(5sin(π/2-a)+cos(π/2)-a))/(2cos(π+a)-sin(-a))的值
已知sin(3π+a)=2cos(a-4π),求(5sin(π/2-a)+cos(π/2)-a))/(2cos(π+a)-sin(-a))的值
sin(3π+a)=2cos(a-4π)
-sina=2cosa
sina=-2cosa
sina/cosa=-2
tana=-2
[5sin(π/2-a)+cos(π/2-a)]/[2cos(π+a)-sin(-a)]
=[5cosa+sina]/[-2cosa+sina](分子分母同时除以cosa)
=(5+sina/cosa)/(-2+sina/cosa)
=(5+tana)/(-2+tana)
=(-5-2)/(-2-2)
=(-7)/(-4)
=7/4